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EXPERIMENTAL STUDIES ON CONVERSION OF WASTE
POLYSTYRENE TO STYRENE AND LIQUID FUEL
A THESIS SUBMITTED IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
Bachelor of Technology
in
Chemical Engineering
By
NITIN KUMAR (10600024)
Under the Guidance of
Prof. R.K.SINGH
Department of Chemical Engineering
National Institute of Technology
Rourkela-769008, Orrisa, India
May 2010
National Institute of Technology, Rourkela
EXPERIMENTAL STUDIES ON CONVERSION OF WASTE
POLYSTYRENE TO STYRENE AND LIQUID FUEL
A THESIS SUBMITTED IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
Bachelor of Technology
in
Chemical Engineering
By
NITIN KUMAR (10600024)
Under the Guidance of
Prof. R.K.SINGH
Department of Chemical Engineering
National Institute of Technology
Rourkela-769008, Orrisa, India
May 2010
National Institute of Technology, Rourkela
CERTIFICATE
This is to certify that the thesis entitled, “EXPERIMENTAL STUDIES ON CONVERSION OF
WASTE POLYSTYRENE TO STYRENE AND LIQUID FUEL” submitted by Mr. Nitin
Kumar in partial fulfilments for the requirements for the award of Bachelor of Technology Degree
in Chemical Engineering at National Institute of Technology, Rourkela (Deemed University) is an
authentic work carried out by him under my supervision and guidance.
To the best of my knowledge, the matter embodied in the thesis has not been submitted to any other
University / Institute for the award of any Degree or Diploma.
Date
PROF. R.K.SINGH
Dept .of Chemical Engineering
National Institute of Technology
Rourkela – 769008
ACKNOWLEDGEMENT
I express my sincere gratitude to Prof. R.K.SINGH (Faculty Guide) and Prof.H.M.Jena (Project
Coordinator), of Department of Chemical Engineering, National Institute of Technology, Rourkela,
for their valuable guidance and timely suggestions during the entire duration of my project work,
without which this work would not have been possible.
I owe a depth of gratitude to Prof. S.K. Aggarwal ,H.O.D., Department of Chemical Engineering,
for all the facilities provided during the tenure of entire project work. I want to acknowledge the
support of all the faculty and friends
Of Chemical Engineering Department, NIT Rourkela.
I thank to the support and good wishes of my parents and family members, without which i would
not have been able to complete my thesis.
Date: 07/05/2010
Nitin Kumar
CONTENTS
Page No.
Abstract i
List of Figures ii
List of Tables iii-iv
Chapter 1
INTRODUCTION
1.1 Styrene 3-6
1.2 Polystyrene 7-9
1.3 Polymerisation of styrene 10-12
Chapter 2
LITERATURE REVIEW
2.1 Various Degradation techniques of Polystyrene 14-16
Chapter 3
EXPERIMENTAL PROCEDURES
3.1 Sample Preparation 18-19
3.2 Experimental Procedure and Set-up 19-20
3.3 Thermo-gravimetric Analysis of Sample 21-22
3.4 Fourier Transform Infrared Spectroscopy Analysis 22-24
3.5 Detailed Hydrocarbon Analysis 24-26
Chapter 4
RESULTS AND DISCUSSIONS
4.1 Thermal Pyrolysis 28-29
4.2 Catalytic Pyrolysis-1 29-31
4.3 Catalytic Pyrolysis-2 31-31
4.4 Fourier Transform Infrared Spectroscopy of the liquid product 33
4.5 Detailed Hydrocarbon Analysis of the liquid product 34
Chapter 5
CONCLUSION 37-38
REFERENCES 39-40
ABSTRACT
The degradation of waste polystyrene sample was carried out in the temperature range of 450-575
„c by both thermal degradation and by catalytic degradation using SILICA-ALUMINA as catalyst.
It was found that liquid product yield increases with increasing temperature in both thermal as well
as catalytic degradation till 550‟c , afterwards liquid product yield starts decreasing with increasing
temperature. In second stage to find out optimum polystyrene : silica-alumina ratio for maximum
liquid product yield , catalytic degradation of polystyrene was carried out at 550‟c in various
proportion, i.e. 20:1 , 15:1 , 10:1 , 5:1 and 4:1. It was found that liquid product yield increases with
increasing the ratio of catalyst upto 5:1 and afterwards increasing the catalyst ratio has resulted in
decreasing the amount of liquid product. It was also found that styrene was the main constituents of
liquid product ,about 86 % , in thermal degradation of polystyrene at 550‟c while in catalytic
pyrolysis done in 5:1 ratio at the same temperature has only 41 % styrene in the liquid product
obtained. This study indicates that mechanism of degradation depends on the temperature of
degradation as well as amount of catalyst used for degradation.
.
(i)
List of tables
Table No. Title Page No.
Table 1.1 hazards related to styrene 5-6
Table 1.2 some important addition polymers and their monomers 11
Table 1.3 Tm and Tg values for some common addition polymers 12
Table 2.1 Catalytic Degradation of polystyrene by different investigators 14
Table 2.2 Supercritical degradation of polystyrene in different solvents at
350 °C by different investigators 16
Table 4.1 Observation Table - 1 (for thermal pyrolysis) 28
Table 4.2 Observation Table - 2 (for catalytic pyrolysis) 29
Table 4.3 Observation Table - 3 (for catalytic pyrolysis) 31
(ii)
List of Figures
Figure No. Title Page No.
Fig 1.1 Symbol for recycled polystyrene products 3
Fig 1.2 Common household products made from polystyrene 3
Fig 3.1 Collected samples of waste polystyrene 18
Fig 3.2 Reduced polystyrene sample 18
Fig 3.3 Crushed polystyrene sample 19
Fig 3.4 Reactor 19
Fig 3.5 Pyrolysis SET-UP 20
Fig 3.6 TG-Analysis of polystyrene sample 22
Fig 3.7 Gas chromatograph principle 26
Fig 3.8 GC-MS principle 26
Fig 4.1 Temp Vs yield of liquid product in thermal pyrolysis of PS 28
Fig 4.2 Temp Vs yield of liquid,solid & gaseous products in thermal
pyrolysis of PS 29
Fig 4.3 Temp Vs yield of liquid product in catalytic (10:1) pyrolysis
of PS 30
Fig 4.4 Temp Vs yield of liquid, solid & gaseous products in catalytic
(10:1) pyrolysis of PS 30
(iii)
Fig 4.5 Temp Vs yield of liquid products in thermal as well as catalytic
(10:1) pyrolysis of PS 31
Fig 4.6 Temp Vs yield of liquid, solid & gaseous products in catalytic
pyrolysis of PS 32
Fig 4.7 Amount of silica-alumina Vs yield of liquid product in catalytic
pyrolysis of PS 32
Fig 4.8 FT-IR Analysis of liquid product obtained by catalytic pyrolysis
(silica-alumina) of PS sample at 550`c (5:1) 33
Fig 4.9 DHA Analysis of liquid products obtained from thermal as well
as catalytic (silica-alumina) pyrolysis (PS:catalyst=5:1) done
with silica-alumina at 550‟c of polystyrene sample. 34
(iv)
Chapter 1
Introduction
(1)
INTRODUCTION
Petrochemical based plastics, produced annually on the 100 million ton scale, pervade modern
society as a result of their versatile and highly desirable properties. However, once disposed of,
many of these plastics pose major waste management problems due to their recalcitrance.
15 million metric tons of polystyrene are produced annually worldwide, most of which ends up in
landfill. Hence, the conversion of waste polystyrene (a dead end product) into a useful commodity
is desirable. As a result of its widespread use and poor rate of recycling, polystyrene is viewed as a
major post-consumer waste product.
In the U.S. alone, over 3 million tons of polystyrene are produced annually, 2.3 million tons of
which end up in a landfill. Furthermore only 1-2% of post-consumer polystyrene waste was
recycled in the U.S. in 2005. The poor rate of polystyrene recycling is due to direct competition
with virgin plastic on a cost and quality basis. Consequently, there is little or no market for recycled
polystyrene. As an alternative to polymer recycling, polystyrene can be burned to generate heat and
energy or converted back to its monomer components for use as a liquid fuel. A number of
techniques for converting plastic back to its monomer components have been developed, one of
which, pyrolysis, involves thermal decomposition in the absence of air to produce pyrolysis oils or
gases. In addition to their use as fuels, pyrolysis oils may also have a biotechnological use, i.e., as a
starting material for the bacterial synthesis of value added products. Due to the biotechnological
conversion of polystyrene to PHA, post consumer polystyrene is, potentially, a starting material for
the synthesis of biodegradable plastic. Indeed this work creates a substantive link between
petrochemical and biological polymers and potentially opens up a new area of exploration for the
petrochemical industry.
The disposal of waste plastic materials is an extreme problem which has a high environmental
impact. In the last years, there has been increasing concern about the recycling of these waste
materials, for which a number of different options exist. All the alternatives have some drawbacks:
for example, direct reprocessing (primary recycling) can only be applied up to a certain limit;
combustion (secondary recycling) may produce harmful gases, and landfilling has environmental
risks due to the chemical inertness of these materials. The tertiary recycling implies the conversion
of the polymers into more valuable chemicals or fuels, technological implementations depending on
the type of polymers to be recycled.
(2)
Fig 1.1 Symbol for recycled polystyrene products
Fig 1.2 common household products made from polystyrene
1.1 STYRENE
Styrene is flammable liquid ,very refractive, with a strong pungent but tolerable and quickly
disappearing odour at ambient air levels of 100 ppm. The odour detection limit is around 5 ppm.
(3)
Synonyms : Vinylbenzene
Phenylethylene
Ethenylbenzene
Chemical formulae : C8H8 / C6H5CHCH2
Molecular mass: 104.2
1.1.1 PHYSICAL PROPERTIES
APPEARANCE:
COLOURLESS TO YELLOW OILY LIQUID.
Boiling point: 145°C
Melting point: -30.6°C
Relative density (water = 1): 0.91
Solubility in water, g/100 ml at 20°C: 0.03
Vapour pressure, kPa at 20°C: 0.67
Relative vapour density (air = 1): 3.6
Relative density of the vapour/air-mixture at 20°C (air = 1): 1.02
Flash point: 31°C c.c.
Auto-ignition temperature: 490°C
Explosive limits, vol% in air: 0.9-6.8
Relative density: 0.9059 at 25°C
Vapour pressure: 10 mm at 35°C
Saturation vapour concentration: 6600 ppm at 20°C
Solubility: practically insoluble in water;
soluble in alcohol, ether, methanol, acetone and
carbon disulfide.
Kinematic viscosity at 20°C : 0.8 cSt
Kinematic viscosity at 100°C : 0.4 cSt
Coefficient of volume Expansion at 20°C: 0.979x10-3
/°C
Specific heat at 20°C : 1.73 kJ/kg.°C
1.1.2 CHEMICAL DANGERS
The substance can form explosive peroxides. The substance may polymerize due to warming, under
the influence of light, oxidants oxygen, and peroxides , causing fire and explosion hazard. Reacts
violently with strong acids, strong oxidants causing fire and explosion hazard. It Attacks rubber,
copper and copper alloys.
1.1.3 OCCUPATIONAL EXPOSURE LIMITS
TLV: 20 ppm as TWA; 40 ppm as STEL; A4 (not classifiable as a human carcinogen); BEI issued
(ACGIH 2005). MAK: 20 ppm, 86 mg/m³; Peak limitation category: II(2); Carcinogen category: 5;
Pregnancy risk group: C.
ROUTES OF EXPOSURE:
The substance can be absorbed into the body by inhalation of its vapour.
INHALATION RISK
A harmful contamination of the air will be reached rather slowly on evaporation of this substance at
20°C.
EFFECTS OF SHORT-TERM EXPOSURE:
The substance is irritating to the eyes, the skin and the respiratory tract. Swallowing the liquid may
cause aspiration into the lungs with the risk of chemical pneumonitis.The substance may cause
effects on the central nervous system. Exposure at high levels may result in unconsciousness.
EFFECTS OF LONG-TERM OR REPEATED EXPOSURE:
The liquid defats the skin. The substance may have effects on the central nervous system. Exposure
to the substance may enhance hearing damage caused by exposure to noise. This substance is
possibly carcinogenic to humans.
Table 1.1 Hazards related to styrene
TYPES OF HAZARD
/ EXPOSURE
ACUTE HAZARDS /
SYMPTOMS PREVENTION
FIRST AID / FIRE
FIGHTING
FIRE Flammable. Gives off
irritating or toxic
fumes (or gases) in a
fire.
NO open flames, NO
sparks, and NO
smoking.
Dry powder. Foam.
Carbon dioxide.
EXPLOSION Above 31°C explosive
vapour/air mixtures
may be formed. See
Notes.
Above 31°C use a
closed system,
ventilation, and
explosion-proof
electrical equipment.
In case of fire: keep
drums, etc., cool by
spraying with water.
(5)
EXPOSURE STRICT HYGIENE
Inhalation Dizziness. Drowsiness.
Headache. Nausea.
Vomiting. Weakness.
Unconsciousness.
Ventilation, local
exhaust, or breathing
protection.
Fresh air, rest. Refer
for medical attention.
Skin Redness. Pain. Protective clothing.
Protective gloves.
Remove contaminated
clothes. Rinse and then
wash skin with water
and soap.
Eyes Redness. Pain. Safety goggles, or eye
protection in
combination with
breathing protection.
First rinse with plenty
of water for several
minutes (remove
contact lenses if easily
possible), then take to
a doctor.
Ingestion Nausea. Vomiting. Do not eat, drink, or
smoke during work.
Rinse mouth. Do NOT
induce vomiting. Give
plenty of water to
drink. Rest.
1.1.4 ENVIRONMENTAL CONCERN
The substance is toxic to aquatic organisms. It is strongly advised that this substance should not
enter the environment.
1.1.5 INDUSTRIAL APPLICATIONS
The technical material is usually 99.6% pure, and normally contains a very small amount (12 to 15
ppm) of tertiary butyl catechol as a polymerisation inhibitor. When heated to 200°C it is converted
into the polymer, polystyrene. Styrene can react violently with oxidizing agents such as peroxides,
strong acids, and chlorates. Fires involving styrene may release dangerous by-products specially
carbon dioxiode and carbon monoxide. Fires must be extinguished with carbon dioxide or dry
chemical.
Several millions of tons of styrene are used world-wide in the production of polystyrene,styrene-
butadiene co-polymer for synthetic rubber,styrene-acrylonitrile polymer,acrylonitrile-butadiene-
styrene copolymer,polyester resins for reinforced fiberglass products, paints,coatings, in the
manufacture of reinforced plastics,and as insulators.
(6)
1.2 POLYSTYRENE
IUPAC NAME : Poly(1-phenylethane-1,2-diyl)
sometimes abbreviated PS, is an aromatic polymer made from the aromatic monomer styrene, a
liquid hydrocarbon that is commercially manufactured from petroleum by the chemical industry.
Polystyrene is one of the most widely used kinds of plastic.Polystyrene is a thermoplastic
substance, which is in solid (glassy) state at room temperature, but flows if heated above its glass
transition temperature (for molding or extrusion), and becoming solid again when cooling off. Pure
solid polystyrene is a colorless, hard plastic with limited flexibility. It can be cast into molds with
fine detail. Polystyrene can be transparent or can be made to take on various colors.
Solid polystyrene is used, for example, in disposable cutlery, plastic models, CD and DVD cases,
and smoke detector housings. Products made from foamed polystyrene are nearly ubiquitous, for
example packing materials, insulation, and foam drink cups.
Polystyrene can be recycled, and has the number "6" as its recycling symbol. Unrecycled
polystyrene, which does not biodegrade, is often abundant in the outdoor environment, particularly
along shores and waterways, and is a form of pollution.
1.2.1 GENERAL PROPERTIES
The chemical makeup of polystyrene is a long chain hydrocarbon with every other carbon
connected to a phenyl group (the name given to the aromatic ring benzene, when bonded to
complex carbon substituents). Polystyrene's chemical formula is (C8H8)n; it contains the chemical
elements carbon and hydrogen. Because it is an aromatic hydrocarbon, it burns with an orange-
yellow flame, giving off soot, as opposed to non-aromatic hydrocarbon polymers such as
polyethylene, which burn with a light yellow flame (often with a blue tinge) and no soot. Complete
oxidation of polystyrene produces only carbon dioxide and water vapor.
(7)
consider polystyrene's properties based on its structure shown above. Polystyrene is chemically
unreactive (this is why it is used to create products such as containers for chemicals, solvents and
foods). This stability is the result of the transformation of carbon-carbon double bonds into less
reactive single bonds. The strong bonds within the molecule make styrene very stable.
Polystyrene is generally flexible and can come in the form of mouldable solids or viscous liquids.
The force of attraction in polystyrene is mainly van der Waals attractions between chains. Since the
molecules may have carbon chains that are thousands of atoms long the overall van der Waals
attraction force is very large. Although the over all force of attraction is large, van der Waals
attractions are individually very weak. It is this weakness that allows the polystyrene chains to slide
along each other rendering polystyrene itself flexible and stretchable. It can be softened and
moulded by heat.
1.2.2 TYPES OF POLYSTYRENE
Polystyrene is commonly produced in three
forms: extruded polystyrene, expanded
polystyrene foam, and extruded
polystyrene foam, each with a variety of
applications. Polystyrene copolymers are
also produced; these contain one or more
other monomers in addition to styrene. In
recent years the expanded polystyrene
composites with cellulose and starch have
also been produced.
Extruded polystyrene foam insulation is
sold under the trademark Styrofoam by
Dow Chemical. This term is often used
informally for other foamed polystyrene products.
Polystyrene is also used in some polymer-bonded explosives.
(8)
Properties
Density 1050 kg/m³
Density of EPS 25-200 kg/m³
Dielectric constant 2.4–2.7
Specific gravity 1.05
Electrical conductivity (s) 10-16 S/m
Thermal conductivity (k) 0.08 W/(m·K)
Young's modulus (E) 3000-3600 MPa
Tensile strength (st) 46–60 MPa
Elongation at break 3–4%
Notch test 2–5 kJ/m²
Glass temperature 95 °C
Melting point[3] 240 °C
Vicat B 90 °C[4]
Linear expansion coefficient (a) 8 10-5 /K
Specific heat (c) 1.3 kJ/(kg·K)
Water absorption (ASTM) 0.03–0.1
Decomposition X years, still decaying
1.2.3 Disposal and environmental issues
Polystyrene is not easily recycled because of its light weight (especially if foamed) and its low scrap
value. It is generally not accepted in kerbside recycling programs. In Germany, however,
polystyrene is collected, as a consequence of the packaging law (Verpackungsverordnung) that
requires manufacturers to take responsibility for recycling or disposing of any packaging material
they sell.
On the other hand, great advances have been made in recycling expanded polystyrene at an
industrial level. Many different methods of densification have been developed.Some industrial
polystyrene manufacturers accept post consumer EPS for recycling. As an example Dart Container
Corporation in Mason, Michigan has an ongoing post consumer recycling operation as well as an
industrial EPS scrap recycling operation.
Discarded polystyrene does not biodegrade and is resistant to photolysis.However, very little of the
waste discarded in today's modern, highly engineered landfills biodegrades. Because degradation of
materials creates potentially harmful liquid and gaseous by-products that could contaminate
groundwater and air, today's landfills are designed to minimize contact with air and water required
for degradation, thereby practically eliminating the degradation of waste.
Foamed kinds of discarded polystyrene often not only float on water, but also blow in the wind, it
has the potential to be abundant in the outdoor environment due to people littering, particularly
along shores and waterways.
1.2.4 Incineration
If polystyrene is properly incinerated at high temperatures, the only chemicals generated are water,
carbon dioxide, some volatile compounds, and carbon soot. According to the American Chemistry
Council, when polystyrene is incinerated in modern facilities, the final volume is 1% of the starting
volume; most of the polystyrene is converted into carbon dioxide, water vapor, and heat. Because of
the amount of heat released, it is sometimes used as a power source for steam or electricity
generation.
(9)
1.3 POLYMERISATION OF STYRENE
GENERAL INFORMATIONS
In 1996, world production capacity for styrene was near 19.2 million metric tonnes per year. Dow
Chemical is the world's largest producer with a total capacity of 1.8 million metric tonnes in the
USA, Canada, and Europe (1996 figures). The main manufacturing route to styrene is the direct
catalytic dehydrogenation of ethylbenzene:
The reaction shown above has a heat of reaction of -121 KJ/mol (endothermic). Nearly 65% of all
styrene is used to produce polystyrene.
The overall reaction describing the styrene polymerization is:
This reaction is carried out in an inert organic solvent environment which provides the reaction
medium for this cationic polymerization reaction. The most common solvent used for this reaction
is 1,2-dichloroethane (EDC). Other suitable solvents may include carbon tetrachloride, ethyl
chloride, methylene dichloride, benzene, toluene, ethylbenzene, or chlorobenzene. The preferred
initiator is a mixture of boron trifluoride and water.
(10)
Table 1.2 some important addition polymers and their monomers
Some Common Addition Polymers
Name(s) Formula Monomer Properties Uses
Polyethylene low density (LDPE)
–(CH2-CH2)n– ethylene CH2=CH2
soft, waxy solid film wrap, plastic bags
Polyethylene high density (HDPE)
–(CH2-CH2)n– ethylene CH2=CH2
rigid, translucent solid
electrical insulation bottles, toys
Polypropylene (PP) different grades
–[CH2-CH(CH3)]n–
propylene CH2=CHCH3
atactic: soft, elastic solid isotactic: hard, strong solid
similar to LDPE carpet, upholstery
Poly(vinyl chloride) (PVC)
–(CH2-CHCl)n–
vinyl chloride CH2=CHCl
strong rigid solid pipes, siding, flooring
Poly(vinylidene chloride) (Saran A)
–(CH2-CCl2)n– vinylidene chloride CH2=CCl2
dense, high-melting solid
seat covers, films
Polystyrene (PS)
–[CH2-CH(C6H5)]n–
styrene CH2=CHC6H5
hard, rigid, clear solid soluble in organic solvents
toys, cabinets packaging (foamed)
Polyacrylonitrile (PAN, Orlon, Acrilan)
–(CH2-CHCN)n–
acrylonitrile CH2=CHCN
high-melting solid soluble in organic solvents
rugs, blankets clothing
Polytetrafluoroethylene (PTFE, Teflon)
–(CF2-CF2)n– tetrafluoroethylene CF2=CF2
resistant, smooth solid
non-stick surfaces electrical insulation
Poly(methyl methacrylate) (PMMA, Lucite, Plexiglas)
–[CH2-C(CH3)CO2CH3]n–
methyl methacrylate CH2=C(CH3)CO
2CH3
hard, transparent solid
lighting covers, signs skylights
Poly(vinyl acetate) (PVAc)
–(CH2-CHOCOCH3)n
–
vinyl acetate CH2=CHOCOCH3
soft, sticky solid latex paints, adhesives
cis-Polyisoprene natural rubber
–[CH2-CH=C(CH3)-CH2]n–
isoprene CH2=CH-C(CH3)=CH2
soft, sticky solid requires vulcanization for practical use
Polychloroprene (cis + trans) (Neoprene)
–[CH2-CH=CCl-CH2]n–
chloroprene CH2=CH-CCl=CH2
tough, rubbery solid synthetic rubber oil resistant
(11)
On heating or cooling most polymers undergo thermal transitions that provide insight into their
morphology. These are defined as the melt transition, Tm , and the glass transition, Tg . Tm is the
temperature at which crystalline domains lose their structure, or melt. As crystallinity increases, so
does Tm. Tg is the temperature below which amorphous domains lose the structural mobility of the
polymer chains and become rigid glasses.
Tg often depends on the history of the sample, particularly previous heat treatment, mechanical
manipulation and annealing. It is sometimes interpreted as the temperature above which significant
portions of polymer chains are able to slide past each other in response to an applied force. The
introduction of relatively large and stiff substituents (such as benzene rings) will interfere with this
chain movement, thus icreasing Tg. The introduction of small molecular compounds called
plasticisers into the polymer matrix increases the interchain spacing, allowing chain movement at
lower temperatures with a resulting decrease in Tg.
Table 1.3 Tm and Tg values for some common addition polymers are listed below
Polymer LDPE HDPE PP PVC PS PAN PTFE PMMA Rubber
Tm (ºC) 110 130 175 180 175 >200 330 180 30
Tg (ºC) _110 _110 _20 80 90 95 _110 105 _70
1.3.1 Four General Polymerization Procedures are
• Radical Polymerization : The initiator is a radical, and the propagating site of reactivity is a
carbon radical.
• Cationic Polymerization : The initiator is an acid, and the propagating site of reactivity is a
carbocation.
• Anionic Polymerization : The initiator is a nucleophile, and the propagating site of reactivity
is a carbanion.
• Coordination Catalytic Polymerization : The initiator is a transition metal complex, and
the propagating site of reactivity is a terminal catalytic complex.
(12)
Chapter 2
LITERATURE REVIEW
(13)
2.1 DEGRADATION OF POLYSTYRENE TO STYRENE
The degradation of polystyrene to styrene can be done by following methods:
I. Thermal degradation.
II. Catalytic degradation.
III. Photo-catalytic degradation.
IV. Super critical solvent oxidation method.
(1) Waste polystyrene can be converted to styrene by simple thermal degradation at 873 Kelvin but
this high degradation temperature needs to be lowered by using different catalysts as it makes the
conversion and recycling process expensive. The main problems of thermal degradation of
polystyrene have been found to be a tendency to produce cokes and jam the apparatus, caused by
the high viscosity of melting polymer and low heat transfer rate. Different methods have been used
to reduce cokes.
(2) Catalytic degradation has been researched widely. By the help of suitable catalysts we can lower
the temperature of thermal degradation from 873 to about 650 Kelvin in addition catalysts also
make the process fast with low production of undesired products [1-9].
Table 2.1 Catalytic Degradation of polystyrene by different investigators
(14)
(3) Waste polystyrene can be converted to styrene by simple photo-catalytic degradation at room
temperature. The TiO2 catalyst modified by iron (II) phthalocyanine , in order to improve its
photocatalytic efficiency, was used by investigators for degradation of polystyrene under the
visible light irradiation as well as UV irradiation in this experiment. The main problems of photo-
catalytic degradation was found to be low (30-35%) efficiency of degradation of polystyrene. It was
reported by investigators that the benzene rings in PS matrix of the composite film were cleaved
during UV-light irradiation [12].
(4) Supercritical water oxidation (SCWO) is a rapidly emerging-waste-treatment method that has
attracted many researchers' interests. Supercritical water dissolves polystyrene, which does not
dissolve in water at ambient temperature and atmospheric pressure. Various investigators obtained
high yield of styrene monomer using SCWO to pyrolyse polystyrene. Though SCWO has many
advantages in cracking polymeric materials, simultaneously it causes rapid corrosion to apparatus at
so rigorous operating condition (temperature over 380 °C and pressure over 20 MPa).When
benzene, toluene, ethylbenzene and p-xylene were used as supercritical solvents to depolymerise
polystyrene, toluene used as supercritical solvent gave higher yields of styrene than other solvents.
This implies supercritical solvents affect the reaction mechanism of polystyrene degradation
differently. The conversion of polystyrene was close to complete degradation when the temperature
reached 370 °C. Supercritical degradation in toluene improved the liquid product yield close to 97%
while reducing the gas and residue oil to less than 1% and 3%, respectively. Compared with thermal
degradation solvent-less, supercritical toluene provides a mild environment for degradation and
transfers heat from medium to the polymer chain quickly and uniformly. Benzene, toluene,
ethylbenzene and p-xylene can be used as supercritical solvents to depolymerise polystyrene. The
results of different investigators indicated solvents affected the reaction mechanism differently [10-
11].
Table 2.2 Supercritical degradation of polystyrene in different solvents at
350 °C by different investigators
Supercritical solvent Benzene Toluene Ethylbenzene p-Xylene Thermal
Yields of liquid (wt.%) 79.1 85.8 79.8 79.0 81.7
Compositions of liquid (wt. %)
Benzene – 4.21 1.79 28.4 0
Toluene 13.7 – 14.6 15.6 5.1
Ethylbenzene 24.8 3.69 – 29.2 2.4
Xylene 21.3 1.20 6.59 – 0
Styrene 33.8 88.0 49.5 18.4 70.0
α-methylstyrene 4.71 2.52 15.3 2.27 8.6
Dimer 0.36 0.38 1.20 2.02 11.2
Yields of styrene (wt. %) 26.7 75.5 39.5 14.5 57.2
(16)
Chapter 3
EXPERIMENTAL PROCEDURE
(17)
Thermal and catalytic pyrolysis of polystyrene in batch
reactor
3.1 Sample preperation
1) The waste polystyrene sample materials were collected from waste yard of NIT-RKL campus.
2) The soft and high volume thermocole ( expanded polystyrene ) samples were first kept inside the
electric oven at 80‟c for one hour. This resulted in a low volume reduced hard brittle mass sample.
3) This hard brittle mass was then grounded to small pieces/powder by the help of hammer mill.
4) This powdered/small pieces of thermocole sample can now be subjected to thermal / catalytic
pyrolysis.
Fig 3.1 Collected samples of waste polystyrene
Fig 3.2 Reduced polystyrene sample
(18)
Fig 3.3 Crushed polystyrene sample
3.2 Description of pyrolysis set-up
Reactor
It was a stainless steel tube of length 145 mm,internal diameter 37 mm and outer diameter 41 mm
sealed at one end and an outlet tube at other end. The reactor was heated externally by putting it
inside an electrical furnace.
Fig 3.4 Reactor
Furnace
The furnace used for the pyrolysis operation was an electrical furnace with the temperature being
measured by a Cr:Al K type thermocouple fixed inside the furnace. The temperature of the furnace
was controlled by an external PID controller.
(19)
Fig 3.5 Pyrolysis SET-UP
3.2.1 Procedure of pyrolysis :
About 15/20 grams of crushed thermocole powder were loaded in each thermal pyrolysis reaction.
In the catalytic pyrolysis a mixture of catalyst and the thermocole powder in various proportions
were subjected to pyrolysis in the SET-UP. The reactor was heated at the rate of 20/25 „c /mint up
to the desired temperature. The condensable liquid product coming from the reactor was collected
by passing them through the condenser and finally collecting them in the measuring flask.
The liquid product collected through the condenser was weighted and it‟s volume was also noted
down for each pyrolysis operation. After completion of pyrolysis operation the solid residue left
out inside the reactor was weighted . Then the weight of gaseous product evolved during
pyrolysis was calculated by MATERIAL BALANCE.
To know the weight loss of the sample as a function of temperature, THERMAL GRAVIMETRIC
ANALYSIS TEST of the sample was done.
(20)
3.3 THERMO-GRAVIMETRIC ANALYSIS
Introduction
Thermo-gravimetric analysis or thermal gravimetric analysis (TGA) is a type of testing that is
performed on samples to determine changes in weight in relation to change in temperature. Such
analysis relies on a high degree of precision in three measurements: weight, temperature, and
temperature change. As many weight loss curves look similar, the weight loss curve may require
transformation before results may be interpreted. A derivative weight loss curve can be used to tell
the point at which weight loss is most apparent. Again, interpretation is limited without further
modifications and deconvolution of the overlapping peaks may be required.
TGA is commonly employed in research and testing to determine characteristics of materials such
as polymers, to determine degradation temperatures, absorbed moisture content of materials, the
level of inorganic and organic components in materials, decomposition points of explosives, and
solvent residues. It is also often used to estimate the corrosion kinetics in high temperature
oxidation.
3.3.1 Procedure of TG Analysis
The analyzer usually consists of a high-precision balance with a pan (generally platinum) loaded
with the sample. The pan is placed in a small electrically heated oven with a thermocouple to
accurately measure the temperature. The atmosphere may be purged with an inert gas to prevent
oxidation or other undesired reactions. A computer is used to control the instrument.
Analysis is carried out by raising the temperature gradually and plotting weight (percentage) against
temperature. The temperature in many testing methods routinely reaches 1000°C or greater, but the
oven is so greatly insulated that an operator would not be aware of any change in temperature even
if standing directly in front of the device. After the data are obtained, curve smoothing and other
operations may be done such as to find the exact points of inflection [13].
3.3.2 Specific measurements made by TGA include:
Moisture and Volatiles Content
Composition of Multicomponent Systems
Thermal Stability
Oxidative Stability
Shelf-Life Studies Using Kinetic Analysis
Decomposition Kinetics
Effect of Reactive Atmospheres
3.3.3 TG ANALYSIS OF WASTE POLYSTYRENE SAMPLE
Fig 3.6 TG-Analysis of polystyrene sample
By thermo-gravimetric analysis test of waste polystyrene sample it was known that pyrolysis, both
thermal and catalytic , should be done in the temperature range of 450-550 „c.
3.4 FOURIER TRANSFORM INFRARED SPECTROSCOPY
INTRODUCTION
FTIR is most useful for identifying chemicals that are either organic or inorganic. It can be utilized
to identify different components of an unknown mixture. It can be applied to the analysis of solids,
liquids, and gasses.
One of the most basic tasks in spectroscopy is to characterize the spectrum of a light source: How
much light is emitted at each different wavelength. The most straightforward way to measure a
spectrum is to pass the light through a monochromator, an instrument that blocks all of the light
except the light at a certain wavelength (the un-blocked wavelength is set by a knob on the
monochromator). Then the intensity of this remaining (single-wavelength) light is measured.
0
20
40
60
80
100
120
0 200 400 600 800
pe
rce
nta
ge w
eig
ht
loss
of
sam
ple
temperature ('c)
THERMO-GRAVIMETRIC ANALYSIS OF WASTE
POLYSTYRENE SAMPLE
% WEIGHT LOSS
The measured intensity directly indicates how much light is emitted at that wavelength. By varying
the monochromator's wavelength setting, the full spectrum can be measured.
In Fourier transform spectroscopy rather than allowing only one wavelength at a time to pass
through to the detector, this technique lets through a beam containing many different wavelengths
of light at once, and measures the total beam intensity. Next, the beam is modified to contain a
different combination of wavelengths, giving a second data point. This process is repeated many
times. Afterwards, a computer takes all this data and works backwards to infer how much light there
is at each wavelength.Between the light source and the detector, there is a certain configuration of
mirrors that allows some wavelengths to pass through but blocks others (due to wave interference).
The beam is modified for each new data point by moving one of the mirrors; this changes the set of
wavelengths that can pass through.computer processing is required to turn the raw data (light
intensity for each mirror position) into the desired result (light intensity for each wavelength). The
processing required turns out to be a common algorithm called the Fourier transform (hence the
name, "Fourier transform spectroscopy"). The raw data is sometimes called an "interferogram". The
technique of "Fourier transform spectroscopy" can be used both for measuring emission spectra and
absorption spectra [14].
3.4.1 Why Infrared Spectroscopy ?
Infrared spectroscopy has been a workhorse technique for materials analysis in the laboratory for
over seventy years. An infrared spectrum represents a fingerprint of a sample with absorption peaks
which correspond to the frequencies of vibrations between the bonds of the atoms making up the
material. Because each different material is a unique combination of atoms, no two compounds
produce the exact same infrared spectrum. In infrared spectroscopy, IR radiation is passed through a
sample. Some of the infrared radiation is absorbed by the sample and some of it is passed through
(transmitted). The resulting spectrum represents the molecular absorption and transmission,creating
a molecular fingerprint of the sample. Like a fingerprint no two unique molecular structures
produce the same infrared spectrum. While organic compounds have very rich, detailed spectra,
inorganic compounds are usually much simpler. For most common materials, the spectrum of an
unknown can be identified by comparison to a library of known compounds.
(23)
To identify less common materials, IR will need to be combined with nuclear magnetic resonance,
mass spectrometry, emission spectroscopy, X-ray diffraction, and/or other techniques.Infrared
spectroscopy useful for several types of analysis. Therefore, infrared spectroscopy can result in a
positive identification (qualitative analysis) of every different kind of material. In addition, the size
of the peaks in the spectrum is a direct indication of the amount of material present.
Informations FT-IR can provide:
• It can identify unknown materials
• It can determine the quality or consistency of a sample
• It can determine the amount of components in a mixture.
3.4.2 Physical Principles
Molecular bonds vibrate at various frequencies depending on the elements and the type of bonds.
For any given bond, there are several specific frequencies at which it can vibrate. According to
quantum mechanics, these frequencies correspond to the ground state (lowest frequency) and
several excited states (higher frequencies). One way to cause the frequency of a molecular vibration
to increase is to excite the bond by having it absorb light energy. For any given transition between
two states the light energy (determined by the wavelength) must exactly equal the difference in the
energy between the two states [usually ground state (E0) and the first excited state (E1)]. The energy
corresponding to these transitions between molecular vibrational states is generally 1-10
kilocalories/mole which corresponds to the infrared portion of the electromagnetic spectrum.
3.5 DETAILED HYDROCARBON ANALYSIS (DHA)
introduction
A gas chromatography system for the Detailed Hydrocarbon Analysis of the sample by component
and by group, named DHA, is used to analyze light fractions with final boiling points up to 450°F
(225°C). Samples normally analyzed using this technique are virgin napthas, alkylates, FCC
gasoline, reformates (charge and product), or gases and liquids from the production of propanes and
butanes. Samples containing oxygenated compounds can also be analyzed with this system.
(24)
The DHA analyzer classifies the electronic signals accumulated by the data acquisition system and
uses that signal to identify individual components present in the sample. Subsequently, it reports the
concentrations of the all of the groups specified by the user: Paraffins, Isoparaffins, Aromatics,
Olefins, Napthens and Oxygenates. If the system is equipped with a sulfur selective detector, sulfur
containing compounds present in the sample are also identified. The DHA system, is characterized
by its totally interactive graphics which permit the overlay of chromatograms to discern even the
smallest differences between samples.
3.5.1 GAS CHROMATOGRAPHY (GC)
Introduction
Gas chromatography (GC), is a common type of chromatography used in analytic chemistry for
separating and analyzing compounds that can be vaporized without decomposition. Typical uses of
GC include testing the purity of a particular substance, or separating the different components of a
mixture (the relative amounts of such components can also be determined). In some situations, GC
may help in identifying a compound. In preparative chromatography, GC can be used to prepare
pure compounds from a mixture.
3.5.2 PRINCIPLE OF GC
In a GC analysis, a known volume of gaseous or liquid analyte is injected into the "entrance" (head)
of the column, usually using a microsyringe (or, solid phase microextraction fibers, or a gas source
switching system). As the carrier gas sweeps the analyte molecules through the column, this motion
is inhibited by the adsorption of the analyte molecules either cling onto the column walls or onto
packing materials in the column. The rate at which the molecules progress along the column
depends on the strength of adsorption, which in turn depends on the type of molecule and on the
stationary phase materials. Since each type of molecule has a different rate of progression, the
various components of the analyte mixture are separated as they progress along the column and
reach the end of the column at different times (retention time). A detector is used to monitor the
outlet stream from the column; thus, the time at which each component reaches the outlet and the
amount of that component can be determined. Generally, substances are identified (qualitatively) by
the order in which they emerge (elute) from the column and by the retention time of the analyte [15]
(25)
Fig 3.7 Gas chromatograph Principle
Fig 3.8 GC-MS principle
(26)
Chapter 4
RESULTS AND DISCUSSIONS
(27)
4.1 THERMAL PYROLYSIS
Table 4.1 OBSERVATION TABLE-1 (FOR THERMAL PYROLYSIS)
Thermal pyrolysis of 15
grams of polystyrene
sample
At following temp („c)
Weight of
liquid
Products
obtained
(grams)
Weight of
solid
Products
obtained
(grams)
Weight of
gaseous
Products
obtained
(grams)
Total time
for
Thermal
pyrolysis
(mints)
450 12.54 0.203 2.26 74
475 12.9 0.2 1.9 62
500 13.55 0.18 1.27 47
525 13.52 0.2 1.28 33
550 14.11 0.21 0.68 37
575 13.8 0.2 1.0 35
Amount of liquid product obtained in the thermal pyrolysis of 15 grams of polystyrene sample is
shown below :
Fig 4.1 temp vs yield of liquid product in thermal pyrolysis of PS
12.4
12.6
12.8
13
13.2
13.4
13.6
13.8
14
14.2
400 450 500 550 600
Liq
uid
pro
du
ct o
bta
ine
d (
gms)
Temperature (`c)
Thermal pyrolysis of PS
thermal
Amount of liquid,solid and gaseous product obtained in the thermal pyrolysis of 15 grams of
polystyrene sample is shown below :
Fig 4.2 temp vs yield of liquid, solid & gaseous products in thermal pyrolysis of PS
4.2 CATALYTIC PYROLYSIS - 1
Table 4.2 OBSERVATION TABLE-2 (FOR CATALYTIC PYROLYSIS)
Catalytic pyrolysis of 15
grams of polystyrene
sample
With 1.5 gram silica-
alumina at following temp
(„c)
Weight of
liquid
Products
obtained
(grams)
Weight of
solid
Products
obtained
(grams)
Weight of
gaseous
Products
obtained
(grams)
Total time
for
Thermal
pyrolysis
(mints)
450 12.17 1.65 2.68 68
475 12.88 1.5 2.12 60
500 13.65 0.8 2.05 38
525 13.5 1.13 1.87 38
550 13.77 1.35 1.38 35
575 13.52 1.16 1.82 31
(29)
02468
10121416
400 450 500 550 600
Am
ou
nt
in g
ram
s
Temperature (`c)
Thermal pyrolysis of 15 grams of PS sample
liquid product
residues
gaseous products
Amount of liquid product obtained in the catalytic pyrolysis (10:1) of 15 grams of polystyrene
sample is shown below
Fig 4.3 temp vs yield of liquid product in catalytic (10:1) pyrolysis of PS
Amount of liquid,solid and gaseous product obtained in the catalytic pyrolysis (10:1) of 15 grams
of polystyrene sample is shown below :
Fig 4.4 temp vs yield of liquid, solid & gaseous products in catalytic (10:1) pyrolysis of PS
(30)
12
12.5
13
13.5
14
400 450 500 550 600
Liq
uid
pro
du
ct o
bta
ine
d (
gms)
Temperature ('c)
Catalytic pyrolysis of PS with silica-alumina
catalytic(10:1)
02468
10121416
400 450 500 550 600
Am
ou
nt
in g
ram
s
Temperature (`c)
Catalytic pyrolysis of PS sample with silica-alumina (10:1)
liquid product
residues
gaseous products
Comparative study of liquid products obtained in the thermal and catalytic pyrolysis (10:1) of 15
grams of polystyrene sample is shown below :
Fig 4.5 temp vs yield of liquid products in thermal as well as catalytic (10:1) pyrolysis of PS
4.3 CATALYTIC PYROLYSIS – 2
Table 4.3 OBSERVATION TABLE-3 (FOR CATALYTIC PYROLYSIS)
Catalytic pyrolysis of 15
grams of polystyrene
sample at 550 „c with
following amount of
silica-alumina in grams.
Weight of
liquid
Products
obtained
(grams)
Weight of
solid
Products
obtained
(grams)
Weight of
gaseous
Products
obtained
(grams)
Total time
for
Thermal
pyrolysis
(mints)
0.75 ( 20 : 1 ) 13.42 0.95 1.38 33
1.0 ( 15 : 1 ) 13.54 1.0 1.46 33
1.50 ( 10 : 1 ) 13.77 1.35 1.38 35
3.0 ( 5 : 1 ) 14.74 2.55 0.71 31
3.75 ( 4 : 1 ) 13.30 3.4 2.05 34
(31)
12
12.5
13
13.5
14
14.5
400 450 500 550 600
Liq
uid
pro
du
cts
ob
tain
ed
(gm
s)
Temperature (`c)
Liquid product obtained by thermal and catalytic pyrolysis of PS
thermal
catalytic(10:1)
Amount of liquid, solid and gaseous products obtained in the catalytic pyrolysis of 15 grams of
polystyrene sample at 550 „c with varying amount of silica-alumina ( in grams) is shown below
Fig 4.6 temp vs yield of liquid, solid & gaseous products in catalytic pyrolysis of PS
Amount of liquid product obtained in the catalytic pyrolysis of 15 grams of polystyrene sample at
550 „c with varying amount of silica-alumina ( in grams) is shown below
Fig 4.7 amount of SILICA-ALUMINA vs yield of liquid product in catalytic pyrolysis of PS
(32)
02468
10121416
0 1 2 3 4
Am
ou
nt
in g
ram
s
Amount of catalyst, silica-alumina, used
Catalytic pyrolysis of 15 grams of PS sample
liquid product
residues
gaseous products
13.213.413.613.8
1414.214.414.614.8
15
0 1 2 3 4
Liq
uid
pro
du
ct o
bta
ine
d (
gms)
Amount of catalyst, silica-alumina, used
Catalytic pyrolysis of 15 grams of PS sample
liquid product
4.5 RESULT OF FT-IR TEST
FT-IR of the liquid product obtained by the catalytic (SILICA-ALUMINA) pyrolysis of the waste
polystyrene sample at 550 „c. (Polystyrene : catalyst = 5 : 1)
Fig 4.8 FT-IR Analysis of liquid product obtained by catalytic pyrolysis(silica-alumina) of
polystyrene sample at 550`c (polystyrene : catalyst = 5 : 1)
(33)
4000.0 3600 3200 2800 2400 2000 1800 1600 1400 1200 1000 800 600 400.0
30.0
40
50
60
70
80
90
100
110
120
130
140
150.0
cm-1
%T
3082.71
3060.41
3026.82
2930.22
2857.80
1601.26
1494.64
1452.00
899.13
776.52
746.55
698.77
542.12
494.61
4.6 Result of DHC
The composition of liquid products obtained from thermal as well as catalytic pyrolysis (5:1) done
with silica-alumina at 550‟c is shown below :
Thermolysis of waste thermocol to value added products Prof.R.K.Singh, INDIA.16
Composition
in wt %
Thermal Catalytic
Kaoline
Catalytic
Silica Alumina
C1 0 1.05 1.35
C2 0.12 2.47 1.31
C3 0.16 3.18 5.49
C4 0.06 0.49 0.46
C5 0 0 0
C6 0 0 0
Benzene 2.14 7.14 9.06
Toluene 1.9 8.1 18.21
Ethyl Benzene 6.1 12.84 20.12
Styrene 85.59 62.01 40.95
Xylene 0 0 0.4
C9- aromatics 1.12 0.2 1.3
C10+-aromatics 2.81 2.52 1.35
Compositional analysis of Pyrolysis oil
DHA Analysis of pyrolysis oil
Fig 4.9 DHA Analysis of liquid products obtained from thermal as well as catalytic (silica-alumina)
pyrolysis (PS:catalyst=5:1) done with silica-alumina at 550‟c of polystyrene sample.
(34)
4.4 PRECAUTIONS
1) Weight of sample meant for pyrolysis should be weighted carefully.
2) In case of catalytic pyrolysis sample and catalyst should be mixed thoroughly.
3) Reactor should be thoroughly cleaned of any residues,before putting the sample in it.
4) Condenser as well as measuring flask should be properly cleaned with METHANOL, to get rid
of undesired chemicals present in them.
5) Reactor should be properly sealed to avoid loss of volatile component produced during
pyrolysis.
6) During the process of pyrolysis keen observation should be focused on vent of reactor to know
the temperature at which pyrolysis reaction started. The temperature at which reaction starts can be
known by evolution of gases through vent of reactor connected to condenser.
7) When reaction starts the cold water tap connected to condenser should be turn on.
8) When pyrolysis reaction is over liquid collected in measuring flask should be properly weighted.
9) When the reactor cools down residues left should be carefully taken out and weighted properly
as mass of liquid product and solid residues is used to determine the mass of gaseous products
evolved during the pyrolysis reaction by the MATERIAL BALANCE equation.
(35)
Chapter 5
CONCLUSIONS
(36)
RESULTS OBTAINED FOR THERMAL AND CATALYTIC
PYROLYSIS EXPERIMENTS OF POLYSYRENE
1) It was found that in case of thermal pyrolysis of polystyrene yield of liquid product increased
with increasing temperature and maximum yield was obtained at 550 „c. After 550 „c yield of liquid
product starts decreasing with increasing temperature.
2) It was found that in case of catalytic (10 : 1 = polystyrene : silica-alumina) pyrolysis of
polystyrene yield of liquid product increased with increasing temperature and maximum yield was
obtained at 550 „c. After 550 „c yield of liquid product starts decreasing with increasing
temperature.
3) It was found that liquid yield was more in the case of thermal pyrolysis of polystyrene than that
of catalytic pyrolysis done with SILICA-ALUMINA in 10:1 ratio.
4) It was found that with increasing catalyst ,SILICA-ALUMINA, ratio in catalytic pyrolysis of
polystyrene liquid product obtained had also increased upto 5:1 ratio , i.e. when for every 5 grams
of polystyrene 1 gram of catalyst was used. Afterward increasing catalyst ratio had resulted in
lower yield of liquid product. Experiments done at 550‟c.
5) liquid product obtained by thermal pyrolysis of PS at 550 „c had about 85.6 % of its
constituents as monomer styrene. While liquid product obtained by catalytic pyrolysis with silica-
alumina at 550‟c (5 : 1 = polystyrene : silica-alumina) had about 41 % of its constituents as
monomer styrene. Thus to obtain styrene from waste polystyrene thermal degradation is best
method in compare to catalytic pyrolysis by silica-alumina.
(37)
RESULTS OBTAINED FOR THERMAL AND CATALYTIC
PYROLYSIS EXPERIMENTS OF POLYSYRENE
6) Significant amount of benzene , toluene and ethyl benzene was obtained in catalytic
pyrolysis of polystyrene done with silica-alumina at 550‟c in 5:1. They constitutes 9.06 % ,
18.21% and 20.12 % respectively of the total weight of the liquid products obtained. While
in case of thermal pyrolysis done at 550‟c they constitutes 2.14 % , 1.9 % and 6.1 %
respectively of the total weight of the liquid products obtained. [RESULT FROM DHC
ANALYSIS]
7) yield of lighter fractions in the liquid products was also much higher in case of catalytic
pyrolysis (5:1) than in thermal pyrolysis done at 550‟c. [RESULT FROM DHC ANALYSIS]
(38)
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(39)
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[13] http://en.wikipedia.org/wiki/Thermogravimetric_analysis
[14]http://en.wikipedia.org/wiki/Fourier Transform Infrered Spectroscopy _analysis
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(40)